数据结构与算法 - 链表

双链表的的基本结构

从 STL 源码抽出的基本双链表结构

代码

#ifndef _GRAVER_GLIB_LIST_H_
#define _GRAVER_GLIB_LIST_H_

#include <cstddef>

#include "graver/util/log_util.h"

namespace graver {

// 内部结构与方法放在 detail
namespace detail {

/**
 * @brief 链表结点
 * 
 * @tparam T 数据类型
 */
template <typename T>
class ListNode {
public:
    ListNode() {
        prev = nullptr;
        next = nullptr;
    }

    ListNode(T value) {
        prev = nullptr;
        next = nullptr;
        data = value;
    }

public:
    /**
     * @brief 前一个结点指针
     */
    ListNode<T>* prev;
    /**
     * @brief 后一个结点指针
     */
    ListNode<T>* next;
    /**
     * @brief 数据
     */
    T data;
};

/**
 * @brief 迭代器
 * 
 * @tparam T 数据类型
 */
template <typename T>
class ListIterator {
public:
    ListIterator(ListNode<T>* ptr = nullptr) : _ptr(ptr){};
    T& operator*() const {
        return *static_cast<T*>(static_cast<void*>(&_ptr->data));
    };
    T* operator->() const {
        return static_cast<T*>(static_cast<void*>(&_ptr->data));
    }
    ListIterator& operator++() {
        _ptr = _ptr->next;
        return *this;
    }
    ListIterator operator++(int) {
        auto tmp = *this;
        _ptr     = _ptr->next;
        return tmp;
    }
    bool operator==(const ListIterator& it) const {
        return _ptr == it._ptr;
    }
    bool operator!=(const ListIterator& it) const {
        return _ptr != it._ptr;
    }

private:
    ListNode<T>* _ptr;
};

}  // namespace detail

/**
 * @brief 链表
 * 
 * @tparam T 数据类型
 */
template <typename T>
class List {
private:
    typedef detail::ListNode<T> _Node;

public:
    typedef detail::ListIterator<T> iterator;

public:
    List() {
        dzlog_info("List constructor");
        _head = new _Node();
        _tail = new _Node();

        _head->prev = nullptr;
        _head->next = _tail;
        _tail->prev = _head;
        _tail->next = nullptr;

        _length = 0;
    }
    ~List() {
        dzlog_info("List destructor");
        clear();
        delete _head;
        delete _tail;
    }

public:
    // 返回指向起始的迭代器
    iterator begin() noexcept {
        return iterator(_head->next);
    }
    // 返回指向末尾的迭代器
    iterator end() {
        return iterator(_tail);
    }

public:
    // 是否为空
    bool empty() {
        return 0 == size();
    }
    // 元素数量
    size_t size() const {
        return _length;
    }

public:
    // 清空链表
    void clear() {
        while (!empty()) {
            pop_back();
        }
    }
    // 尾部追加元素
    void push_back(const T& value) {
        detail::ListNode<T>* node = new _Node();
        node->data                = value;

        _tail->prev->next = node;
        node->prev        = _tail->prev;
        node->next        = _tail;
        _tail->prev       = node;

        _length++;
    }

    // 尾部移除
    void pop_back() {
        if (empty()) {
            return;
        }

        auto removeNode = _tail->prev;
        _tail->prev     = removeNode->prev;
        delete removeNode;
        _length--;
    }

private:
    /**
     * @brief 头结点
     */
    _Node* _head;
    /**
     * @brief 尾结点
     */
    _Node* _tail;
    /**
     * @brief 链表长度
     */
    size_t _length;
};

}  // namespace graver

#endif

测试

测试数据定义

#ifndef _GRAVER_TEST_TEST_TYPE_H_
#define _GRAVER_TEST_TEST_TYPE_H_

#include <string>

#include "fmt/core.h"
#include "graver/util/log_util.h"

struct Person {
    std::string name;
    int         age;

    void print() const {
        dzlog_info(fmt::format("name:{}\tage:{}", name, age).c_str());
    }
};

#endif

STL list 测试

#include <list>
#include <memory>

#include "doctest/doctest.h"
#include "fmt/core.h"
#include "graver/util/log_util.h"
#include "test_type.hpp"

TEST_SUITE("test_common") {
    TEST_CASE("test_common_one") {
        auto list = std::make_unique<std::list<Person>>();
        dzlog_info("it++");
        list->push_back({"Thresh", 18});
        list->push_back({"Syndra", 16});
        list->push_back({"Maokai", 35});
        list->push_back({"Shaco", 25});
        for (auto it = list->begin(); it != list->end(); it++) {
            (*it).print();
        }
        dzlog_info("++it");
        for (auto it = list->begin(); it != list->end(); ++it) {
            it->print();
        }
        dzlog_info("foreach");
        for (const auto& p : *list) {
            p.print();
        }
    }
}

自定义双链表测试

#include <memory>

#include "doctest/doctest.h"
#include "fmt/core.h"
#include "graver/glib/glib.h"
#include "graver/util/log_util.h"
#include "test_type.hpp"

TEST_SUITE("test_list") {
    TEST_CASE("test_list_one") {
        auto list = std::make_unique<graver::List<Person>>();
        dzlog_info("it++");
        list->push_back({"Thresh", 18});
        list->push_back({"Syndra", 16});
        list->push_back({"Maokai", 35});
        list->push_back({"Shaco", 25});
        for (auto it = list->begin(); it != list->end(); it++) {
            (*it).print();
        }
        dzlog_info("++it");
        for (auto it = list->begin(); it != list->end(); ++it) {
            it->print();
        }
        dzlog_info("foreach");
        for (const auto& p : *list) {
            p.print();
        }
    }
}

输出结果

2023-06-28 07:21:24.978 6716 INFO [test_type.hpp:14] - name:Thresh      age:18
2023-06-28 07:21:24.978 6716 INFO [test_type.hpp:14] - name:Syndra      age:16
2023-06-28 07:21:24.978 6716 INFO [test_type.hpp:14] - name:Maokai      age:35
2023-06-28 07:21:24.978 6716 INFO [test_type.hpp:14] - name:Shaco       age:25
2023-06-28 07:21:24.979 6716 INFO [test_list.cpp:20] - ++it
2023-06-28 07:21:24.979 6716 INFO [test_type.hpp:14] - name:Thresh      age:18
2023-06-28 07:21:24.979 6716 INFO [test_type.hpp:14] - name:Syndra      age:16
2023-06-28 07:21:24.979 6716 INFO [test_type.hpp:14] - name:Maokai      age:35
2023-06-28 07:21:24.979 6716 INFO [test_type.hpp:14] - name:Shaco       age:25
2023-06-28 07:21:24.980 6716 INFO [test_list.cpp:24] - foreach
2023-06-28 07:21:24.980 6716 INFO [test_type.hpp:14] - name:Thresh      age:18
2023-06-28 07:21:24.980 6716 INFO [test_type.hpp:14] - name:Syndra      age:16
2023-06-28 07:21:24.980 6716 INFO [test_type.hpp:14] - name:Maokai      age:35
2023-06-28 07:21:24.981 6716 INFO [test_type.hpp:14] - name:Shaco       age:25